Henry David Thoreau, Forest Succession, and the Nature of Science:
A Method for Curriculum Development
ERIC M. HOWE
Education Department, Assumption College
Worcester, MA 01609, U.S.A. (e-mail: [email protected])
Abstract: Episodes from the history of science can provide a useful context for students to learn aspects of the
nature of science. Research documents the importance of having students learn the nature of science in an explicit
and reflective manner in order to facilitate their conceptual understanding of nature of science tenets. This paper
presents one method for curriculum development that draws from three areas, 1) how to research a selected episode
from the history of science, 2) how to identify germane nature of science tenets exemplified in the historical
episode(s), and 3) how to develop a problem-based approach using the historical episodes to promote students
explicit and reflective examination of issues associated with the nature of science. The method is discussed with
reference to an example from the history of ecology and introductory forest succession involving the work of Henry
David Thoreau.
A main reason for using the history of science in classroom instruction is its utility in promoting students’
understanding of the nature of science (NOS). Through history of science, students can interpret such
NOS tenets as: how scientific knowledge is generated, how it is subject to mechanisms of potential
change, how it is validated, and how it differs from other ways of knowing about the world. As indicated
in such documents as the National Science Education Standards, it is important to help students’ develop
their understanding of NOS so that they will become more critical consumers of the very scientific
knowledge that increasingly impacts their daily lives (National Research Council, 1996).
Science education research draws attention to the importance of having students explicitly and
reflectively consider NOS tenets during instruction (Howe & Rudge, 2005; Khisfhe & Abd-El-Khalick,
2002). Explicit learning means that through some aspect of instruction, one or more of the relevant NOS
tenets are directly targeted for students to evaluate. This can be contrasted with implicit learning of NOS,
whereby the claim is that students simply ‘pick up’ NOS understanding when they engage in various
content or process learning in science. Reflective learning underscores that students must be challenged to
develop their own conceptual understanding of the NOS tenets, in contrast to the alternative (didactic)
approach in which an instructor ‘tells’ students how the NOS tenet applies to a given situation.
Another important consideration for NOS instruction is the degree to which it is imbedded in a
context (Clough, 2006). On one end of the spectrum, there are decontextual approaches which involve
exposing students to various ‘black box’ activities (Lederman & Abd-El-Khalick, 1998) and having them
explicitly/reflectively examine germane NOS tenets. These can be very powerful introductions to NOS,
but as Clough (2006) points out when students only learn such tenets in a decontextual approach, they
may leave instruction with a dualistic conception of NOS – believing that what occurs in ‘real science’ is
distinct from that learned during the decontextual activity.
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Using history of science in instruction is a potential contextual approach for students to explicitly
and reflectively learn NOS tenets, and science education literature contains numerous examples of its use
in this regard (Howe & Rudge, 2005; Monk & Osborne, 1997; Khisfhe & Abd-El-Khalick, 2002; Rudge,
2004; Solomon, Duveen, Scot & McCarthy, 1992). Indeed, these studies provide empirical efficacy
(albeit modest) that the instrumental use of history of science can help students develop more informed
nature of science conceptions. While these studies effectively present varied ways that history has been
used in this regard, they do not provide sufficient detail for curriculum developers to replicate their
approaches (how to go about identifying and connecting relevant aspects of the history of science to the
important nature of science tenets).
This paper provides a method for teachers who intend to use one or more episodes from the
history of science to help students explicitly and reflectively learn more informed nature of science
conceptions. The method facilitates:
1. How to research an episode from the history of science for potential classroom use
2. How to identify germane NOS tenets exemplified in the episode
3. How to design classroom problems that have students explicitly and reflectively consider NOS
using the historical episode.
An example of this approach is given using the work of Henry David Thoreau and introductory concepts
of ecological forest succession. Though many of the specific elements of the Thoreau lessons are
discussed in the next sections, for the sake of space only the salient features are highlighted. Full lesson
plans are available from the author upon request.
Phase 1: Researching the History of the Scientific Topic
Virtually all science topics have relevant aspects of the history of science for potential use in the
classroom. A challenge for teachers is often to sufficiently narrow the search about the topic in order to
identify, evaluate, and (where necessary) modify 1 the historical details for their use. A suggested starting
place for research is to use relevant Internet and library search engines to identify if another party (e.g.,
historian of science, science educator, philosopher of science, etc.) has already done work in the area of
interest. When doing the research, it is helpful to think in terms of identifying any problems (conceptual
or empirical) that scientists were trying to solve. Further, it is important to find out if there were
competing ideas to the problem(s) in question and how scientists worked to resolve them.
In the midst of background research, it is important for developers to consider two important
frames of reference. The first involves finding out as much detail as possible about the work of past
scientists on the specific topic that will be the focus of what students might potentially examine in the
classroom. The second frame involves more general research to identify any larger ideas or philosophical
positions (or changes) that may have impacted the way in which the scientist(s) developed their ideas
during the time (or topic) of specific interest.
For example, I was particularly interested in having students learn about introductory community
ecology concepts (e.g. competition, resources, biotic and abiotic factors, dispersion, succession) with
reference to the topic of forest succession. I was also interested in having students develop their
understanding of aspects of the nature of science through the use of any history of scientific work on
ecological succession. I began by consulting several history of science (e.g., Bowler & Morus, 2005) and
history of ecology textbooks (Worster, 1994) in order to learn about the development of ideas in ecology
and to understand how the philosophical commitments in ecology had evolved. This led to my
identifying several items that formed the philosophical backdrop for the progression of ideas in ecology:
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•
•
•
•
The role of a divine creator in living communities
The rise and influence of the inductive approach (Baconian Tradition) to studying science (i.e.,
ecology)
Communities as actions of individual organisms vs. communities as organic wholes (debates of
reductionism vs. holism)
Mechanistic vs. Romantic Philosophies in Science
This research revealed two episodes that seemed potentially useful for teaching students about
forest succession and the nature of science. The first summarized the ecology interests of the New
England naturalist, Henry David Thoreau. The second detailed the more modern ecological debates
between the holistic/organismic succession theorists vs. the individualists, made largely with reference to
the work of Frederick Clements vs. Henry Gleason from the period 1900 – 1930s. The remainder of this
section introduces the Thoreau episode as an example for researching the specific historical details for
potential use in the classroom.
The next step in historical research involved my identifying any conceptual or empirical
‘problems’ that the scientist(s) were trying to resolve. It is useful to think about the work of past scientists
in a problem solving framework (qua Laudan, 1977), because in so doing, the teacher will begin to
conceptualize different explanations (and the pieces of evidence used to support them) potentially worthy
of using in his or her own curriculum development. Often, the citations present in the larger history of
science texts (in this case ecology) refer to specific books or articles that address the work of the scientists
of interest. These secondary sources will often provide a summary of the research problems that the
scientists were striving to solve, and they may likely connect the context of the problem to some of the
larger philosophical themes that were identified in the introductory research. Furthermore, these sources
might include portions (e.g., quotes, data, etc.) from the scientist(s) of interest or at the very least provide
valuable citations of the primary works of the scientist(s) for the researcher to locate.
When looking at these specific resources, it is helpful to use several guiding questions, bearing in
mind that often the answers are explicitly addressed:
•
•
•
•
•
What was the problem that the scientist(s) was trying to resolve?
What lines of evidence did s/he gather?
What explanation resulted from this work?
What explanations existed prior to (or in competition with) the scientist’s work?
What evidence was used to support the prior explanations?
In the case of Thoreau’s work, I found several articles written in the 1950s by a historian of science who
was interested in whether or not Thoreau’s research exemplified a scientific pursuit (Whitford, 1950,
1951). By using the above guiding questions when reading these articles, the following ‘picture’ began to
emerge: Thoreau maintained an acute interest in natural history of his native countryside in central New
England throughout his relatively brief life. Part of his passion for natural history stemmed from his
affinity for the Romantic Movement – whose followers believed in the importance of countering the
increasing exploitation of the environment. They held central beliefs that nature was capable of renewal
and revitalization and that living organisms (of which humans played only a part) were bound together in
an almost a spiritual and metaphysical interrelationship. In addition, Thoreau’s burgeoning interest in the
systematic study of nature stemmed from his evident commitment to a Mechanistic Philosophy – a
philosophy linked closely to the methods developed from the Scientific Revolution.
Well before Thoreau’s time, the work of Newton, Descarte, Gallileo, Kepler, and others in the
physical sciences during the 16th and 17th centuries collectively created what has come to be known as the
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Mechanistic Philosophy for studying the physical realm, namely that all physical entities (including living
organisms) were analogous to machines, and as such, scientists should explain their behavior strictly in
terms of mechanical interactions amongst their parts. This contrasts with previous understandings of the
natural world, which often made reference to mystical or metaphysical considerations to account for
natural phenomena.
Before Thoreau’s time (the mid 19th century) the natural sciences (i.e. biology) had yet to make a
substantive mechanistic transition. Natural scientists like Linneaus and Cuvier continued to proclaim that
God created species of organisms and that He also designed a hierarchy of living things whereby each
organism was dependent on one another. Linneaus believed in the balance of nature whereby species (e.g.
predator / prey) responded to one another so as to maintain a stasis of numbers. Linnaeus frames this with
reference to the design of a benevolent God who desires balance and consistency in nature.2 Living things
were viewed in more holistic terms as having an essence or vitalism that was not simply reducible to the
operation of mere parts, and further the design of the benevolent God ensured that each organism was
created and existed in balance with each other in their respective environments.
Thoreau’s writings (see Whitford, 1950, 1951 and Cafaro, 1998) reveal that his interest in natural
history was motivated by two ironically conflicting philosophical commitments. His holistic feelings
about nature reflected the ideals of the Romantic Movement; He was passionately committed to
environmental conservation, because he witnessed firsthand the reduction of forests and environment in
and around his native home, and he was inspired by early holistic writers of nature (e.g., Gilbert White of
Selbourne, England). His writings reveal a holistic worldview that seeks to understand how everything in
nature interacts almost purposefully to produce a harmonious and self-sustaining whole. Yet his scientific
observations drew from the mechanistic philosophy and inductive approaches to studying nature. Here,
his writings support his interest in the systematic observational analysis of the interrelationships of living
things. This is reflected in the amount of time he spent observing and recording the life history of various
plants (termed phenology) in and around central Massachusetts. This work he placed in a series of
Journals from the period of approximately 1845 to 1860.
I used the history of science (Bowler & Morus, 2005) and ecology (Worster, 1994) texts and the
Whitford articles (1950, 1951) to summarize the above context for Thoreau’s work. The Whitford articles
and Thoreau’s writings (1906a, 1993) revealed that Thoreau was particularly interested in studying a
curious problem related to the succession of wood (forest) lots. Because he was well known in his
community as a naturalist, Thoreau’s advice on various issues was periodically sought, and it is apparent
from his writings that he was often called upon by local farmers to resolve how tree species replaced one
another in certain forest stands. I subsequently refer to this as the ‘Farmers’ Problem’:
THE FARMERS’ PROBLEM
In the mid 19th century a significant proportion of manufactured goods were made from wood,
and because of this forestry (forest management) had become an important industry in New England.
Farmers were vitally interested in understanding how to properly raise, cultivate, harvest, and most
importantly maintain forest stands. Around the time of the 1850s farmers in Concord, Massachusetts kept
asking why when they cut off a stand of lumber in a particular lot of forest, it would often ‘come back’ as
an entirely different species of tree. For example, cut hardwood (e.g. oak) in a woodlot would be replaced
by pitch pine (e.g. white pine), and when farmers cut a pine stand the same ground came up later as
hardwood.
Whitford (1950) gives a cogent summary of several of the prevailing explanations that Thoreau’s
contemporaries held to account for the emergence of new tree species (Table 1), including the belief that
new species were the result of divine intervention, having arisen from special creation or spontaneous
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generation. Table 1 presents a summary of the various explanations, including Thoreau’s ultimate claim
that tree succession in the Farmer’s Problem resulted primarily from differential seed dispersal,
germination, and seedling survival. The table also summarizes the evidence presented in the Whitford
article and from Thoreau’s own writings (1906a) which either support or refute the various explanations
to account for the replacement of tree species in the Farmers’ Problem.
[Insert Table 1 here]
What is particularly noteworthy of Thoreau’s approach to the problem is his use of a careful
systematic method to understand how new species could arise. He gathered data on the various species of
deciduous and coniferous trees that existed in relation to the sites of succession. He studied the methods
(and rates) of seed dispersal, the germination of seeds, the conditional survival of seedlings, and the
habitats and foraging characteristics of various woodland birds and rodents. From this corpus of data he
was able to propose his provisional theory to account for the Farmers’ Problem (owing to differences in
seed dispersal and germination), and he was also able to refute many of the prevailing explanations that
relied upon faith or tenuous conjecture.
It is important to point out that I had to critically read the research pieces (Whitford, 1950;
Thoreau, 1906a) to identify the various explanations to account for the Farmers’ Problem. I did this by
using the guiding questions mentioned earlier in this section when I read through the various pieces and
making note of explanations as they were raised (sometimes implicitly) in the texts. In doing this, I
discovered an additional primary source (Caldwell, 1808) that Thoreau himself relied upon when making
his case for his theory to account for forest succession.
Teachers who replicate this approach will find that some explanations will be more explicitly
addressed than others. It is also important to keep a running list of any evidence (or in the case of some
explanations, an allegiance to authority or faith) that support or refute the various explanations that
emerged. This information is critical when it is time to identify the germane NOS tenets from the research
(discussed in the next phase) and when it is time to package everything into a potential lesson or unit for
students to consider (discussed in phase 3).
Phase 2: Identifying Germane NOS Tenets
Essentially speaking, the nature of science (NOS) deals with understanding the unique aspects of
scientific knowledge or scientific ways of knowing. Stakeholders in science education (e.g. Clough,
2006b; Matthews, 1994; McComas, 2005) largely agree that there are fundamental tenets about NOS that
students should be learning in the classroom. A partial list of these tenets underscores that scientific
knowledge is (c.f., Abd-El-Khalick & Lederman, 2000):
•
•
•
•
•
empirically-based (observations of the natural world)
tentative (subject to potential change)
subjective (theory-laden)
partially based on human inference and creativity
socially and culturally embedded
While lists such as these are certainly important for drawing attention to the multifaceted character of
NOS, they alone are not conducive for teachers who want to develop curriculum that infuses NOS
instruction into the lessons. This is because the tenets as given do not explicitly help teachers link the
conceptual material that they intend to use in the classroom with the relevant aspects of NOS.
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For this reason, teachers would benefit from thinking about potential NOS instruction not in
terms of tenets but in terms of NOS guiding questions (Clough, 2006b; Howe, forthcoming). From the
practical standpoint of taking the research done in the prior section, this would involve examining the list
of scientists’ explanations (and evidentiary support) with the following NOS guiding questions in mind:
[insert Table 2 here]
Specific to the work of Thoreau, I used many of these guiding NOS questions when reading the various
research articles and when examining my summary lists of explanations (and evidence). Using guiding
NOS questions in this way was also very helpful when I made the transition to thinking about ways of
promoting students to explicitly consider NOS tenets in connection with their examining the conceptual
problems. I used many of the specific questions (Table 2) during my curriculum development, but I
altered them below to a form more conducive for students to use as NOS probes to consider during
instruction (see third phase of the method):
NOS Tenet: Empirical Nature of Science-Scientists gather data through their sensory
observations/input
• Is Thoreau’s approach scientific? Why or why not?
• What actions (or methods) did Thoreau use that you feel characterize him as scientific?
Are there any that do not?
Part of what embodies a scientific approach is that it relies on empirically derived data.
Thoreau made specific observations of the behavior of various tree species (their lifecycles)
and the behavior of various forest inhabitants (e.g. rodents, squirrels). Using specific data,
Thoreau deduced that the most parsimonious explanation was that the mechanism for tree
succession related to the reproductive methods of seed dispersal and germination.
Thoreau also believed in Linnaeus’ claims of organismal hierarchies, which in today’s
interpretive lens is seen as metaphysical. This hierarchy proclaimed that some organisms by
their very essence were superordinal to others – more advanced as ordained by creation.
Evidence from Thoreau’s writings suggest that he believed that some species of trees (e.g.
oaks) were the final species (now referred to as climax) in a stand of forest because they were
destined to be so according to the hierarchical framework.
NOS Tenet: Science vs. Pseudoscience
• What distinguishes Thoreau’s explanation to account for the Farmers’ Problem from the
(then) widely held belief that trees arose spontaneously?
The belief that new tree species could arise spontaneously aligned with a divine interpretation
of life. Here, species were seen as created by God and placed upon the dominion of the earth.
The succession of an existing tree species by an entirely new species could be explained by
this, however, the explanation is not scientific. It is based upon manifest faith in the work of a
creator and is such not subject to potential refutation. Thoreau’s explanation is subject to
potential tests to refute it.
NOS Tenet: Scientists are Partially and Unavoidably Subjective in Their Work (and the
Development of Theories) – The Theory-laden Nature of Science
• Might have Thoreau’s prior philosophical orientation influenced how he ‘interpreted’ the
Farmers’ Problem?
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Thoreau embraced the mechanistic philosophy for developing explanations in science. He did
not believe in scientific explanations necessarily tied to ‘higher powers’ or the manifest work
of a ‘creator’. In fact, Thoreau’s writings support that he believed in the evolution of species.
Following a mechanistic perspective, Thoreau believed that natural explanations had causes
that were attributable to individual actions that could be identified and isolated.
NOS Tenet: Scientists use Creativity to Develop Hypotheses/Theories
• What aspects of Thoreau’s work on the Farmers’ Problem would you regard as
‘creative’? Why?
• Do you think contemporary scientists use similar creative processes?
Thoreau must have had creative insights to examine and assimilate the observations he made
in order to link the distribution of seeds by squirrels (etc.) to the reproductive benefit gained
by the trees. It also took creativity to link that squirrels collect and transport seeds as food
with the corollary that trees use this process as a beneficial dispersion. Finally, Thoreau was
creative in drawing an analogy between crop rotation that farmers normally do with the
natural process of seed dispersal and renewal (succession).
Phase 3: Designing instruction to have students explicitly and reflectively consider NOS using the
historical episode.
The ultimate goal is to take the information gathered from the first and second phase of the curriculum
development and package it into one or more lessons to meet the overarching instructional objectives.
DESIGNING BACKGROUND INFORMATION
That students may lack sufficient background information is certainly an important consideration
when designing the lessons. This may inhibit their ability to critically evaluate the context of the problem
that will form the basis for their examination at some point during the lesson. Because of this, teachers
need to think carefully how to preface the problem with enough historical detail to best prepare students
for the lesson, and sufficient background information can take many forms. Sometimes, in order that
students are able to make sense of a problem subsequently given to them, they need sufficient prerequisite
conceptual knowledge (i.e. specific biology or physics concepts). An example of this is in a developed
unit of instruction (c.f. Howe, forthcoming; Howe & Rudge, 2005) based upon the method outlined in this
paper. In this case, students consider a scientific problem based on the mid-20th century work of
geneticists and ecologists who were studying the relationship of the sickle-cell gene (genetics) with the
parasitic disease malaria. Here, it was necessary that students have sufficient conceptual understanding of
introductory genetics models and an understanding of the mechanisms of the malaria life cycle for them
to be able to critically evaluate the central problem. In other cases, students will primarily need enough
background detail of the interests of a particular scientist, the philosophical leanings of that scientist, and
information about any history of ideas, etc. that provides a context for the problem. This is certainly the
case with the Thoreau example discussed in this paper.
For the Thoreau lessons, I began the first day of instruction by briefly (15 minutes) giving
students a summary account of Thoreau’s interests in natural history, his commitment to the empirical
methods derived from the Scientific Revolution, and the influence of his Romantic perspectives on his
understanding of nature. During the subsequent lesson, students were invited to read transcripts from
Thoreau and from his contemporaries, much in the spirit of a case-study approach so that they could
interpret the evidence and conclusions made by the actual scientists of the period. The selection of these
transcripts came as a result of the initial phase of curriculum development.
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DESIGNING THE PROBLEM OF INTEREST
Designing the central problem is of course one of the more critical and time-consuming aspects of
the curriculum development, and teachers must use their ingenuity to take aspects of the work that they
conducted in the first phase of research and modify it for their own pedagogical purposes. Some episodes
from the history of science (i.e. the problems that are identified and the evidence that is used to solve
them) avail themselves to having students look at data. Sometimes the data can be taken directly from the
history of research and modified slightly for ease of use in the classroom. This was the case in the sicklecell approach I developed (Howe & Rudge 2005). Other times, the teacher will need to think about the
conceptual issues raised in the problem (i.e. the explanations and the evidence) and invent a contrived
scenario representative of the issues raised in the problem. This was the case with the Thoreau episode.
In this case, I took the information that emerged from the historical research (encapsulated in Table 1) and
invented a problem for students to consider (The Farmers’ Problem: Appendix A)3.
Once students have been given the appropriate background information, the teacher can then
provide them with the central problem to consider (Appendix A). The emphasis during instruction is to
put students in an active role, whereby in small groups they are encouraged to consider the
problem/evidence given to them and come up with one or more explanations to account for the evidence.
In the Thoreau case, student groups are encouraged to specify between the evidence that they are given,
the inferences that they make from the evidence, any questions that they have, and any proposed
explanations that they develop. Their ideas are placed on the board for comparative purposes during the
whole class session that followed. Group work is then followed with whole class discussions where the
various explanations are shared among members and the teacher can have students comment on the merit
of each other’s answers. Moreover, the teacher can offer additional explanations to account for the
problem in those instances in which students did not develop a particular one.
CONNECTING TO NOS
Recall that the second phase of the method for developing curriculum involves identifying
relevant NOS tenets using guiding questions that help link the specific work of the scientist(s) to the
larger NOS morals. The guiding questions that were used during this process are particularly useful for
having students try to connect the work that they are doing in examining the scientific problem, their own
explanations to account for it, and the explanations proposed by the various scientists themselves. At
some point in this process, the instructor can provide student groups NOS probes for them to consider.
As exemplified in the Thoreau lessons, following the initial class, as homework students were
asked to read through an article written by Thoreau (1906a) in which he presents his specific argument to
explain the succession of forest trees (essentially his account of the Farmers’ Problem). Students were
also provided an excerpt from another article where Thoreau makes additional observations related to tree
succession (Thoreau, 1906b) and they were given excerpts from other naturalists who proposed
alternative explanations. Students were challenged to identify the various explanations (and evidence
for/against) that Thoreau himself discusses. At the same time, students were given NOS probing
questions to consider while they were reading the historical pieces. These NOS probes were taken directly
from the second phase of NOS research that I had done where I had identified any germane NOS tenets.
The idea was to have students consider the NOS questions in concert with the problem they had attempted
to solve during class and with the readings that captured Thoreau’s argument to the problem.
In the subsequent class (day 2), students were invited to share Thoreau’s perspective, and this
information was placed on the board next to what the students had proposed from the previous class.
During a whole-class discussion, students were challenged to critically evaluate the various explanations,
and they were invited to reflect upon the NOS questions given to them. In this way, NOS is a planned
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instructional event (explicit), and because students are put in the position of their having to consider the
NOS probing questions in concert with the work that they did to interpret the problem, they are
challenged to reflectively link NOS to a specific (i.e. scientifically meaningful) context.
CONCEPT LEARNING
Though the above discusses a method for using history of science to promote students’ critical
reasoning and NOS understanding, it is certainly the case that this approach avails itself to promote
concept learning. A major consideration for selecting an episode in the history of science is precisely its
utility in helping students to understand relevant concepts. In the case of the Thoreau lessons, I was
particularly interested in finding an episode in the history of science that could help students learn very
introductory concepts in community ecology (e.g. species, resources, competition, niche, succession,
fitness, etc.). At the same time that a teacher is considering how to package her/his research on the history
of the episode into a potential lesson/unit, she/he can also decide which germane concepts are represented
in the problems that will be given to the students. In the specific Thoreau lessons, students were invited to
read an introductory piece about community ecology and forest succession. They were given concepts to
consider in bullet form and were asked to develop a concept map that represented their interpretation of
these concepts. During instruction, after students had presented their ideas about the Farmers’ Problem, I
led a whole-class discussion in which individual students helped develop a single concept map on the
board that depicted their community understanding.
Summary: Advantages of this Method
The preceding method describes how to integrate explicit/reflective NOS instruction using problem-based
lesson(s) developed from episodes in the history of science. The advantages of this approach draw support
from several areas within science education and cognitive science research.
First, the method assumes as its basis that science is essentially a problem-solving endeavor
(Laudan 1977). Therefore, to the extent possible, lessons that hope to expose students to learning ‘about
science’ should be done in a manner consistent with how scientists operate. It is for this reason that the
method stresses to teachers that they use certain guiding questions to flush out the significant problems of
interest, the evidence that the scientists used to develop explanations to account for the problems, and the
disparities (if applicable) in explanations that were proposed. Correspondingly, placing a curricular
emphasis on explanations and evidence aligns with what science educators point out as fundamental
processes in science (Duschl, 1990), and it avails itself to having students develop critical reasoning in
argumentation (Monk & Osborne 1997).
Second, the method links NOS instruction to what is a context-rich learning experience with the
history of science. The advantage of this as discussed by Clough (2006) is that when students learn NOS
within a contextual framework they are less likely to exit instruction with dualistic thinking of NOS
tenets. Put another way, when NOS instruction is not linked to context (e.g. when NOS is only taught
using ‘black box’ activities) students are more inclined to consider NOS as something that only applies in
terms of the decontextual activity and not with respect to the practice of real science.
Finally, the method draws from research (Abd-El-Khalick & Lederman, 2000; Howe & Rudge,
2005; Khishfe & Abd-El-Khalick, 2002) that demonstrates the importance and efficacy of promoting
students to both explicitly and reflectively learn fundamental NOS tenets. Here, the central argument is
that NOS tenets should be viewed as cognitive constructs and as such are things that students must
meaningfully learn on their own, with the instructor helping to scaffold their concept learning. Thus,
instruction must provide opportunities for students to build upon their existing conceptions of science. In
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this method, the reflective element of NOS probes and subsequent small group and whole-class
discussions emphasizes qua the constructivist philosophy the cognitive learning of NOS.
Very modest empirical efficacy of this method has been demonstrated in a unit of instruction
based upon the history of research in understanding the disease sickle-cell anemia (Howe & Rudge,
2005). The present Thoreau example has been implemented in an undergraduate introductory biology
course, and the author will be collecting an initial round of empirical data using the VNOS, Views of
Nature of Science (Lederman, Abd-El-Khalick, Bell & Schwartz, 2002) in subsequent offerings of the
course.
References
Abd-El-Khalick, F. & Lederman, N. (2000) The influence of history of science courses on students' views
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Bowler, P. & Morus, I. (2005) Making modern science: A historical survey. The University of Chicago
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students’ NOS views explicitly and reflectively. Science & Education 14(3):423-441.
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This paper is being presented at the 2007 IHPST Conference, Calgary in June 2007.
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Lederman, N., Abd-El-Khalick, F., Bell, R., & Schwartz, R. (2002) Views of nature of science
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1
Sometimes it is necessary to modify the historical ‘story’ for pedagogical purposes. Caution is warranted here.
Modify can take many forms. For example, teachers should feel free to add to or alter (often simplify) the evidence
that past scientists examined in order that the problems students examine are tractable for them. Modify does not
mean teachers should falsify history or present pseudohistory as cautioned by Allchin (2004). This would occur
when suggesting that a scientist proposed a particular claim (or explanation) or relied upon a piece of evidence that
simply was not historically accurate (i.e. misrepresenting the historical record).
2
Bowler, P. & Morus, I. (2005).
3
The Farmers’ Problem handout contains some data that seemingly has little bearing on the central issue of this
article. This is because the same handout was used again by students (with additional species data) in a subsequent
11
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exploration of a more contemporary succession problem that encapsulated the historical debates between Frederick
Clements and Henry Gleason. Lesson plans for this problem are also available from the author.
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Table 1
Tree species succeed (or arise) because:
Explanation
Spontaneous Generation (the
divine creation of replacement
species)
Evidence in Support or Against
•
•
•
•
Seeds Lie in Ground For
Many Years and Await
Favorable Conditions for
Germination
•
Stump Sprouts Around
Recently Cut Trees Must
Produce New Growth
•
Seed Dispersal and
Germination
(Thoreau’s Explanation)
•
•
•
•
•
This was believed by many of Thoreau’s contemporaries
Aligned with a belief in divine creation of species
Thoreau explicitly indicates in his writing (Journals) that he
sees no evidence to support this
Thoreau points out how non-native trees in New England
could not simply ‘arise’ from nowhere but must rather have
been brought to America from the outside.
Thoreau gathered acorns of oaks and placed them in a drawer
for six months; Subsequent germination was poor.
For oaks, he either had to accept that seeds could lie dormant
in the ground or come up with another explanation for their
distribution
This would not explain succession of one species to or by
another.
Thoreau points out that sprout regeneration actually makes for
a weaker tree.
Thoreau drew an analogy to pine and maple seeds in relation to
their being carried on the wind.
He made extensive observations of the behavior of squirrels
and their foraging for nuts, noting the tendency of squirrels to
take the heavy nuts of oaks great distances.
Thoreau observed oak seedlings in mature pine forests and
noted that they were seemingly shade tolerant as seedlings.
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Table 2. Guiding NOS Questions
NOS Tenet
•
•
•
Science
demands/relies on
empirical evidence.
Knowledge
production in
science shares
similar methods.
Scientific
knowledge is
tentative, durable
and self-correcting.
Guiding Questions
•
•
•
•
•
•
•
•
•
Science has a
subjective element
(theory-laden
character)
•
•
•
•
Science has a
creative element.
•
•
•
There are historical,
cultural, and social
influences on the
practice of science.
There are historical,
cultural, and social
influences on the
practice of science.
Science and
technology impact
each other, but they
are not the same.
•
•
•
•
•
•
•
In what ways did the past scientist(s) engage in the collection of
data?
Did they conduct observational analyses? Controlled experiments?
Thought experiments?
Were any explanations proposed that lacked empirical evidence?
How did the scientists draw from larger generalizations (laws and/or
theories) to inform their empirical work?
How did their individual data collection lead toward developing their
own generalizations?
Did the scientist’s explanation(s) replace or supplant any existing
ones? Were there alternative theories to account for the available
data?
Were any explanations (or methods used to derive them) found to be
in error?
What caused the replacement of one theory for another? New data?
A new perspective on existing data?
Did technology play a role in bringing about new data?
If there were alternative theories, what differences in backgrounds of
the scientists may help us to understand why they proposed different
explanations? Did they have access to the same (or similar) data?
Were there differences in their educational or philosophical
training/grounding?
How did the scientist(s) achieve his/her insights?
Did he/she draw from other experiences (non-scientific) or creative
endeavors?
How was the scientist’s work influenced by the culture in which
he/she operated?
What ramification may his/her conclusions have on sociological or
political policy?
Did any issues of ethics or values come into play with the historical
episode?
In what way was technology influential in helping the scientist to
collect data in support of his/her work? Was technology a necessary
component?
Did the work of the scientist bring about technological changes or
revolutions?
14
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Appendix A: The Farmers’ Problem
On the next page is a hypothetical diagram of a farmer’s field that is surrounded on three sides by
different forest stands. Below the diagram are illustrations of the species of trees (and their seeds/cones
where applicable) and the annual goldenrod.
Assume that each of the forests (A, B, & C) are at least 40 years old. It is also safe to assume that there
are no other mature species of trees in each of the forests other than those given under the forest headings.
Each forest does contain occasional seedlings trees (approximately 6 to 18 inches tall) of various species,
and each of the forests contains stumps from the cuttings of many years past.
The farmer decides to harvest his pine field (Field C). This is accomplished by literally sawing the mature
trees (largely the entire forest) by cutting them at the base, thereby leaving stumps behind from which
new sprouts may possibly grow (a practice that was commonly done to start tree growth).
Many years pass, and the farmer (or perhaps his/her children) notice that what was once a pine forest in
Field C has now become principally an Oak Forest.
Farmers with other similar plots also notice that in those instances where Oak Fields were harvested for
lumber (like the original Field B), they were eventually replaced by Pine Trees.
Using the information below in the table and the diagram and illustrations on the next page, I want you to
come up with various explanations to account for the farmers’ observations (Where did the Oak trees that
took over the harvested field C come from?). You may decide that much of the information in this table is
not useful for now. You may also decide that you need more information for one or more of your
explanations. That is fine – make note of any questions that you may have. Consider as many
explanations as you can, even those that may seem unusual.
How might someone from the 19th century, who believes in the divine creation of life, explain what is
occurring in the fields?
Species
Avg.
Height
Growth
Rate
Oak
80
Slow
Avg. Age
when
capable of
reproducing
10 years
Pine
60
Slow
10 years
Seed
Dispersal
Drop &
critter
Drop &
Critter
Optimal
Seedling
Light
Conditions
Low light
Adult
Shade
Tolerance
Life
Expectancy
Moderate
80 - 100
Mod. Light
Moderate
50 - 60
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North
Forest B:
Oak (Dense)
Forest A:
Maple (30%)
Pine (40%)
Old Field:
(Grass, Goldenrod)
Pin Cherry (20%)
Forest C:
Pine (Dense)
Blackberry (10%)
(All scattered)
Pine
Cherry
Oak
Maple
Goldenrod
16
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